1. Field of the invention
The present invention relates to an improvement of fundus camera which photographs an image of fundus and more particularly relates to an improvement of fundus camera through which colored fundus images, visible-fluorescent fundus images and infrared-fluorescent fundus images are photographed by Television (hereinafter referred to as xe2x80x9cTVxe2x80x9d) camera.
2. Description of the Related Art
In fundus photographing, because infrared-fluorescent image cannot be photographed by conventional 35 mm film camera or instant camera, TV camera which converts infrared-fluorescent light into TV signal has been generally used for this purpose. Also a 35 mm film camera has been usually employed for photographing colored fundus images and visible-fluorescent images due to its higher resolution. Recently, instead of 35 mm film camera, TV camera is getting popular for photographing visible-fluorescent images and colored images as resolution of CCD for TV camera has been improved.
Meanwhile, with regard to infrared-fluorescent photographing, visible-fluorescent photographing and colored photographing, plurality of TV cameras must be selectively exchanged in accordance with a selection a photographing made, as the wavelength, amount of light or necessary resolution differs according to a selected photographing. Further, because several types of specific designed relay lens units are individually required to adapt respective TV cameras to the fundus camera body, each relay lens unit for respective TV cameras must be exchanged at the same time. To exchange TV camera and its relay lens unit according to the light of photograph is troublesome but inevitable work.
For this problem, the Japanese Patent Application Laid Open Hei 8-256988 proposed a fundus camera in which an optical path length adjusting member is arranged within a TV relay lens unit in order to adjust change of light path length depending on the type of photographing. By this arrangement, the relay lens unit need not be exchanged. However, as TV cameras themselves must be exchanged, it is still inconvenient for users.
The present invention is proposed to solve the above problem and an object of the present invention is to provide a fundus camera having improved operationality which makes it unnecessary to exchange TV camera for fundus photographing.
In accordance with the first aspect of present invention, a fundus camera comprising a body unit having photographing optical system to photograph a fundus to be observed, and TV relay lens unit which is detachably mounted on said body unit and having a function to direct a fundus image forming luminous flux from said photographing optical system to plurality of TV cameras, wherein said TV relay lens unit is arranged to be mountable simultaneously a visible-fluorescent photographing/infrared-fluorescent photographing TV camera having sensitivity for both of visible light and infrared light, a fundus observing TV camera having sensitivity for infrared light to observe a fundus when infrared-fluorescent photographing mode is selected, and a color photographing TV camera having sensitivity for visible light, wherein said TV relay lens unit is equipped with a switching mirror which is retractably and insertably arranged in an optical path of said fundus image forming luminous flux for switching said color photographing TV camera and said visible-fluorescent photographing/infrared-fluorescent photographing TV camera in accordance with the photographing mode, and a reflecting optical element which is arranged between said switching mirror and said color photographing TV camera to direct said fundus image forming luminous flux to said fundus observing TV camera, and said switching mirror is retracted from the optical path of said fundus image forming luminous flux to direct said flux to said fundus observing TV camera for observing a fundus in said infrared-fluorescent photographing mode, and said switching mirror is instantaneously inserted into said optical path to direct said fundus image forming luminous flux to said visible-fluorescent photographing/infrared-fluorescent photographing TV camera for photographing the fundus in said infrared-fluorescent photographing mode, is provided.
According to the second aspect of the invention, a fundus camera of the above described first aspect further characterized in that said reflecting optical element is a dichroic mirror which is selectively passing visible light and reflecting infrared light, is provided.
According to the third aspect of the invention, a fundus camera of the above described first aspect further characterized in that said reflecting optical element is a half mirror, is provided.
According to the fourth aspect of the invention, a fundus camera of the above described first aspect further characterized in that said reflecting optical element is a switching mirror which is insertably or retractably arranged in said optical path to direct said fundus image forming luminous flux to said fundus observing TV camera when it is inserted in said optical path, is provided.
According to the fifth aspect of the invention, a fundus camera comprising a body unit having photographing optical system to photograph a fundus to be observed, and TV relay lens unit which is detachably mounted on said body unit and having a function to direct a fundus image forming luminous flux from said photographing optical system to plurality of TV cameras, wherein said TV relay lens unit is arranged to be mountable simultaneously a visible-fluorescent photographing/infrared-fluorescent photographing TV camera having sensitivity for both of visible light and infrared light, a fundus observing TV camera having sensitivity for infrared light to observe a fundus when infrared-fluorescent photographing mode is selected, and a color photographing TV camera having sensitivity for visible light, and wherein said TV relay lens unit is equipped with first switching mirror which is retracted from the optical path of said fundus image forming luminous flux to direct said fundus image forming luminous flux to said the observing TV camera when infrared-fluorescent photographing mode is selected and the observation thereof is conducted and is instantaneously inserted into the optical path of said fundus image forming luminous flux to direct said fundus image forming luminous flux to said visible-fluorescent photographing/infrared-fluorescent photographing TV camera for infrared-fluorescent photographing mode when photographing the fundus, and second switching mirror which is inserted into the optical path of said fundus image forming luminous flux when color photographing mode is selected, and is retracted from the optical path of said fundus image forming luminous flux when visible-fluorescent photographing mode is selected, is provided.
According to the sixth aspect of the invention, a fundus camera comprising a body unit having photographing optical system to photograph a fundus to be observed, and TV relay lens unit which is detachably mounted on said body unit and having a function to direct a fundus image forming luminous flux from said photographing optical system to plurality of TV cameras, wherein said TV relay lens unit is arranged to be mountable simultaneously a visible-fluorescent photographing/infrared-fluorescent photographing TV camera having sensitivity for both of visible light and infrared light, a fundus observing TV camera having sensitivity for infrared light to observe a fundus when infrared-fluorescent photographing mode is selected and a color photographing TV camera having sensitivity for visible light, and wherein said TV relay lens unit is equipped with first switching mirror which is inserted into the optical path of said fundus image forming luminous flux to direct said fundus image forming luminous flux to said the observing TV camera when infrared-fluorescent photographing mode is selected and the observation thereof is conducted, and is instantaneously retracted from the optical path of said fundus image forming luminous flux to direct said fundus image forming luminous flux to said visible-fluorescent photographing/infrared-fluorescent photographing TV camera for infrared-fluorescent photographing mode when photographing the fundus, and second switching mirror which is inserted into the optical path of said fundus image forming luminous flux when color photographing mode is selected and is retracted from the optical path of said fundus image forming luminous flux when visible-fluorescent photographing mode is selected, is provided.
According to the seventh aspect of the invention, a fundus camera comprising a body unit having photographing optical system to photograph a fundus to be observed, and TV relay lens unit which is detachably mounted on said body unit and having a function to direct a fundus image forming luminous flux from said photographing optical system to plurality of TV cameras, wherein said TV relay lens unit is arranged to be mountable simultaneously a visible-fluorescent photographing/infrared-fluorescent photographing TV camera having sensitivity for both of visible light and infrared light, a fundus observing TV camera having sensitivity for infrared light to observe a fundus when infrared-fluorescent photographing mode is selected and a color photographing TV camera having sensitivity for visible light, and wherein said TV relay lens unit is equipped with first switching mirror which is inserted into the optical path of said fundus image forming luminous flux to direct said fundus image forming luminous flux to said the observing TV camera when infrared-fluorescent photographing mode is selected and observation thereof is conducted, and is instantaneously retracted from the optical path of said fundus image forming luminous flux to direct said fundus image forming luminous flux to said visible-fluorescent photographing/infrared-fluorescent photographing TV camera for infrared-fluorescent photographing mode when photographing the fundus, and second switching mirror which is retracted from the optical path of said fundus image forming luminous flux when color photographing mode is selected and is inserted into the optical path of said fundus image forming luminous flux when visible-fluorescent photographing mode is selected, is provided.
In a fundus camera according to the present invention, as the switching mirror is retracted from the optical path of said fundus image forming luminous flux when color photographing mode is performed by the color photographing TV camera, the visible light component of fundus image forming luminous flux is directed to the reflecting optical element and passed through it to the color photographing TV camera.
And when visible-fluorescent photographing mode is performed by visible-fluorescent photographing/infrared-fluorescent photographing TV camera, as the switching mirror is inserted into the optical path of fundus image forming luminous flux, the visible-fluorescent component of fundus image forming luminous flux is reflected by the switching mirror and directed to the visible-fluorescent photographing/infrared-fluorescent photographing TV camera.
Further, when infrared-fluorescent photographing mode is performed by the visible-fluorescent photographing/infrared-fluorescent photographing TV camera, as the switching mirror is retracted from the optical path of fundus image forming luminous flux when observing a fundus, the infrared-fluorescent component of fundus image forming luminous flux is directed to the reflecting optical element and reflected by it to the fundus observing TV camera, and when photographing the fundus as the switching mirror is instantaneously inserted into the optical path of fundus image forming luminous flux, the infrared-fluorescent component of fundus image forming luminous flux is reflected by the switching mirror and directed to the visible-fluorescent photographing/infrared-fluorescent photographing TV camera.
As described above, because the switching mirror moves according to respective photographing mode and directs the fundus image forming luminous flux to respective TV cameras which are used when each photographing mode is selected, the fundus camera provided in accordance with the present invention has higher operationality which makes it unnecessary to detach one and to mount another for exchange of TV camera for fundus photographing according to light.